Flashlights, radios and other electrical devices frequently require the use of portable electrical supplies in the form of batteries. When the batteries are expended, they must be replaced. This requirement may introduce considerable delay between the time the batteries are expended and the time replacement batteries become available. Furthermore, electrical devices typically do not include a mechanism for indicating the remaining lifetime of the batteries which power the device, frequenlty resulting in expending of the batteries at an inconveninent time.
Therefore, a battery reservoir system is needed which enables a user of an electrical device to select among multiple sets of batteries to power the device when one of the battery sets is consumed.